java-player-users

[Java-player-users] problems using blobfinder

[Alberto A. <ame...@IC...>]

Hello everybody,

This is the first time I am using javaclient and also Player/Gazebo. I 
am trying to detect a blue cylinder using blobfinder, but it's not 
working. I don't know if my problem is the way I am using the java 
client, or might be related with the color file in cmvision, or other 
things.

In the world file, I have a Pioneer2AT robot with a SonyVID30 camera, 
and a couple of SimpleSolids, one of which is a cylinder, with 
<color>0.0 0.0 1</color> (the others are not blue).

Then, in the player file, I have

driver
(
     name "gz_camera"
     provides ["camera:0"]
     gz_id "camera1"
)

driver
(
     name "cmvision"
     provides ["blobfinder:0"]
     requires ["camera:0"]
     colorfile ["colorfile"]
)

The client code I am trying is:

PlayerClient robot = new PlayerClient("localhost", 6665);
BlobfinderInterface bfi = new robot.requestInterfaceBlobFinder(0,'r');
short numBlobs = 0;
bfi.setTrackingColor(0,0,0,0,250,255);
while (true) {
    bfi.readData();
    numBlobs = bfi.getBlobCount();
    System.out.println("num blobs="+numBlobs);
}

I get different values back for num blobs (0, 10, 88, 4608, ...), and 
also sometimes in the client I get an "outofBounds" exception,
"Error when reading payload: java.lang.ArrayIndexOutOfBoundsException: 
256", I guess that the number of "detected" blobs might be too big.

Anybody can help???



Many thanks,

Alberto Amengual

Re: [Java-player-users] problems using blobfinder

[Radu B. R. <ru...@cs...>]

Hello Alberto,

Sorry for replying so late (hmm, looks like I'm the only one actually 
doing that on this mailing list :)). I just uploaded a basic Blobfinder 
example to the Javaclient examples web page. Maybe that will help.

Please modify your source code according to the following guidelines, 
and try again:
- before the while (true), add a line like "robot.runThreaded (-1, -1);"
- remove the "bfi.readData();" from the main while loop;
- add a delay such as "try { Thread.sleep (100); } catch (Exception e) { 
}" in the main while loop.

I don't know about Gazebo, but I will have a look.

Best regards,
Radu.

-- 
| Radu Bogdan Rusu | http://rbrusu.com/
| http://www9.cs.tum.edu/people/rusu/
| Intelligent Autonomous Systems
| Technische Universitaet Muenchen


Alberto Amengual wrote:

> Hello everybody,
>
> This is the first time I am using javaclient and also Player/Gazebo. I 
> am trying to detect a blue cylinder using blobfinder, but it's not 
> working. I don't know if my problem is the way I am using the java 
> client, or might be related with the color file in cmvision, or other 
> things.
>
> In the world file, I have a Pioneer2AT robot with a SonyVID30 camera, 
> and a couple of SimpleSolids, one of which is a cylinder, with 
> <color>0.0 0.0 1</color> (the others are not blue).
>
> Then, in the player file, I have
>
> driver
> (
>     name "gz_camera"
>     provides ["camera:0"]
>     gz_id "camera1"
> )
>
> driver
> (
>     name "cmvision"
>     provides ["blobfinder:0"]
>     requires ["camera:0"]
>     colorfile ["colorfile"]
> )
>
> The client code I am trying is:
>
> PlayerClient robot = new PlayerClient("localhost", 6665);
> BlobfinderInterface bfi = new robot.requestInterfaceBlobFinder(0,'r');
> short numBlobs = 0;
> bfi.setTrackingColor(0,0,0,0,250,255);
> while (true) {
>    bfi.readData();
>    numBlobs = bfi.getBlobCount();
>    System.out.println("num blobs="+numBlobs);
> }
>
> I get different values back for num blobs (0, 10, 88, 4608, ...), and 
> also sometimes in the client I get an "outofBounds" exception,
> "Error when reading payload: java.lang.ArrayIndexOutOfBoundsException: 
> 256", I guess that the number of "detected" blobs might be too big.
>
> Anybody can help???
>
>
>
> Many thanks,
>
> Alberto Amengual

Re: [Java-player-users] problems using blobfinder

[Alberto A. <ame...@IC...>]

Hi Radu,

Thanks a lot, now it works. If you have a minute to briefly explain the 
threading trick, that'd be great. Or maybe you can point me to some doc.

A couple of notes:

* I had to do the request for the blobfinder interface in mode 'r', mode 
'a' causes a segmentation fault, so
"BlobFinderInterface bfi = robot.requestInterfaceBlobfinder(0, 'r');"

* I have tried to track a particular color, but it didn't work. For 
example for orange:
"bfi.setTrackingColor(255,255,128,128,0,0)" but the blobs are still the 
same as without that line. I mean that's no big problem, then I just 
have to go through the blobs and look for the orange one. Probably that 
line is not enough, because on the client I get a "Need to handle a EAR 
message", and on the server "PlayerQueue::Push(): trying to push from 
non-allocated queue".

Best,

Alberto


Radu Bogdan Rusu wrote:

> Hello Alberto,
> 
> Sorry for replying so late (hmm, looks like I'm the only one actually 
> doing that on this mailing list :)). I just uploaded a basic Blobfinder 
> example to the Javaclient examples web page. Maybe that will help.
> 
> Please modify your source code according to the following guidelines, 
> and try again:
> - before the while (true), add a line like "robot.runThreaded (-1, -1);"
> - remove the "bfi.readData();" from the main while loop;
> - add a delay such as "try { Thread.sleep (100); } catch (Exception e) { 
> }" in the main while loop.
> 
> I don't know about Gazebo, but I will have a look.
> 
> Best regards,
> Radu.
> 

Re: [Java-player-users] problems using blobfinder

[Radu B. R. <ru...@cs...>]

Hi Alberto,

The segmentation fault is on Player side. Hopefully v2.0 will not be 
that "picky" on this little details. :)

I am not sure if the Gazebo part (changing the tracked color on the fly) 
is implemented. I know for a fact that it works fine with a CMUcam2 
camera connected to Player, so it might be that the Gazebo driver is not 
supporting it properly.

I'll have a look at Stage today and report later.

Cheers,
Radu.

-- 
| Radu Bogdan Rusu | http://rbrusu.com/
| http://www9.cs.tum.edu/people/rusu/
| Intelligent Autonomous Systems
| Technische Universitaet Muenchen


Alberto Amengual wrote:

> Hi Radu,
>
> Thanks a lot, now it works. If you have a minute to briefly explain 
> the threading trick, that'd be great. Or maybe you can point me to 
> some doc.
>
> A couple of notes:
>
> * I had to do the request for the blobfinder interface in mode 'r', 
> mode 'a' causes a segmentation fault, so
> "BlobFinderInterface bfi = robot.requestInterfaceBlobfinder(0, 'r');"
>
> * I have tried to track a particular color, but it didn't work. For 
> example for orange:
> "bfi.setTrackingColor(255,255,128,128,0,0)" but the blobs are still 
> the same as without that line. I mean that's no big problem, then I 
> just have to go through the blobs and look for the orange one. 
> Probably that line is not enough, because on the client I get a "Need 
> to handle a EAR message", and on the server "PlayerQueue::Push(): 
> trying to push from non-allocated queue".
>
> Best,
>
> Alberto
>
>
> Radu Bogdan Rusu wrote:
>
>> Hello Alberto,
>>
>> Sorry for replying so late (hmm, looks like I'm the only one actually 
>> doing that on this mailing list :)). I just uploaded a basic 
>> Blobfinder example to the Javaclient examples web page. Maybe that 
>> will help.
>>
>> Please modify your source code according to the following guidelines, 
>> and try again:
>> - before the while (true), add a line like "robot.runThreaded (-1, -1);"
>> - remove the "bfi.readData();" from the main while loop;
>> - add a delay such as "try { Thread.sleep (100); } catch (Exception 
>> e) { }" in the main while loop.
>>
>> I don't know about Gazebo, but I will have a look.
>>
>> Best regards,
>> Radu.
>>
>
>
>
>
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